This chart shows that, while some aspects of cognition clearly are in decline as we age, other tests prove that older subjects continue to learn all of their lives. The red lines show that aging reduces working memory, speed, and visual and verbal recall. The yellow lines map the results of vocabulary tests, which is one way to measure world knowledge. World knowledge is seen as remaining steady or improving.
Adapted from Park, Lautenschlager, Hedden, Davidson, Smith and Smith (2001)